Re: insert element into an array

You're splicing onto the wrong array.

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my @R = ([qw(x y z)], [qw(a b c)], [qw(e f g)], [qw(h i j)]);

print Dumper \@R;

for my $rc (@R) {
  if ($rc->[0] eq "a") {
    splice @$rc, 0, 0, '#';
    print "$rc->[0]\t","$rc->[1]\t","$rc->[2]\t","$rc->[3]\n"
  }
}

print Dumper \@R;
[download]

splice @$rc instead of splice @R.

--
<http://www.dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

Comment on Re: insert element into an array Download Code

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Re^2: insert element into an array by Anonymous Monk on Nov 18, 2004 at 12:49 UTC
I obviously have a lot to learn about about the wonders of splice with arrays. If using your example I wanted to delete the row instead of insert a new element, how would I do it ? I tried `for my $rc (@R) { if ($rc->[0] eq "a") { splice @$rc, 0, 2; } }` [download] but this just removes everything (including the line I want to delete) up to the end of the array I also tried this `for my $rc (@R) { if ($rc->[0] eq "a") { delete $rc->[0-2]; } }` [download] This works but then when I try to print the array out I get an uninitialized value in concatenation error. I'd expected this because the array wasn't scrunched up and delete is not the right thing to use I guess. The print I used was `foreach (@records) { $buf .= "$_->[0] $_->[1] $_->[2] $_->[3]\n"; print $buf; }` [download]	[reply] [d/l] [select]
Re^3: insert element into an array by davorg (Chancellor) on Nov 18, 2004 at 15:24 UTC
Once again you're splicing the wrong array :) If you want to remove a row, then you want to alter the outer array, @R. But in this case, splice is really the wrong tool. Here you probably want to use grep. `#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my @R = ([qw(x y z)], [qw(a b c)], [qw(e f g)], [qw(h i j)]); print Dumper \@R; @R = grep { $_->[0] ne 'a' } @R; print Dumper \@R;` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re^4: insert element into an array by Anonymous Monk on Nov 19, 2004 at 10:20 UTC
Many thanks for your reply	[reply]