Re^3: removing elements in array in perl

Ah - I was confused about your double usage of numbers as array elements and array indices.

To me, it feels as if you have a number $n and want to remove $n elements from @A1 and put them into A2:

use strict;
use Data::Dumper;

my @A1 = qw(a b c d e f g);
my $n = 2;
my @A2 = splice @A1, @A1-$n, $n;

print Dumper [\@A1, \@A2];

__END__
$VAR1 = [
          [
            'a',
            'b',
            'c',
            'd',
            'e'
          ],
          [
            'f',
            'g'
          ]
        ];
[download]

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Re^4: removing elements in array in perl by AnomalousMonk (Archbishop) on Nov 23, 2016 at 16:42 UTC
That can be slightly simplified due to the way splice handles a negative `OFFSET`: `c:\@Work\Perl\monks>perl -wMstrict -le "use Data::Dumper; ;; my @A1 = qw(a b c d e f g); my $n = 2; my @A2 = splice @A1, -$n; ;; print Dumper [\@A1, \@A2]; " $VAR1 = [ [ 'a', 'b', 'c', 'd', 'e' ], [ 'f', 'g' ] ];` [download] (If `$n` is greater than the number of elements of the array, a run-time error is thrown.) Update: Actually, the negative offset approach might be significantly better because it throws an error whenever `$n` is greater than the number of array elements, whereas the `splice @A1, @A1-$n, $n` expression produces a silent, possibly unexpected/undesirable aliasing behavior for some values of `$n > @array` and doesn't throw an error until `$n` is greater than twice the number of elements of the array. `c:\@Work\Perl\monks>perl -wMstrict -le "use Data::Dump qw(dd); ;; my @A1 = qw(a b c d e f g); my $n = 14; my @A2 = splice @A1, @A1-$n, $n; ;; dd \@A1, \@A2; " ([], ["a" .. "g"]) c:\@Work\Perl\monks>perl -wMstrict -le "use Data::Dump qw(dd); ;; my @A1 = qw(a b c d e f g); my $n = 15; my @A2 = splice @A1, @A1-$n, $n; ;; dd \@A1, \@A2; " Modification of non-creatable array value attempted, subscript -8 at - +e line 1.` [download] Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^4: removing elements in array in perl by t-rex (Scribe) on Nov 23, 2016 at 09:50 UTC
this works, great thank you	[reply]