Re: Undefined Array Reference

Maybe something like this?

...
for my $i (0..$#$ref_a) {
    push @{$ref_a->[$i]}, @{ ref($ref_b->[$i]) eq 'ARRAY' ?
                             $ref_b->[$i] : [(' ') x 3]   };
    
}
print Dumper($ref_a);
__END__
$VAR1 = [
          [
            'a',
            'b',
            'c',
            'j',
            'k',
            'l'
          ],
          [
            'd',
            'e',
            'f',
            'm',
            'n',
            'o'
          ],
          [
            'g',
            'h',
            'i',
            'p',
            'q',
            'r'
          ],
          [
            'x',
            'y',
            'z',
            ' ',
            ' ',
            ' '
          ],
          [
            '3',
            '4',
            '5',
            ' ',
            ' ',
            ' '
          ],
          [
            '6',
            '7',
            '9',
            ' ',
            ' ',
            ' '
          ]
        ];
[download]

... my interpretation of the "space in the $ref_b" :)

Comment on Re: Undefined Array Reference Download Code

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Re^2: Undefined Array Reference by wol (Hermit) on Apr 23, 2009 at 16:05 UTC
Another interpretation would be "when ref_b runs out of data, don't do anything more to ref_a". If this is what's needed then: `for my $i (0..$#$ref_a) { push @{$ref_a->[$i]}, @{$ref_b->[$i] \|\| []}; }` [download] Ie, if `@{$ref_b}` hasn't got as many members as `@{$ref_a}`, then at some point `$ref_b->[$i]` is undef, so dereference a reference to an empty array in that case. (I also tried to use `\|\| last` there (ie exit the loop early) but that comes up with a "bizarre" error message.) If it's also possible for ref_b to have more members than ref_a, and the extras should be tacked on verbatim, then the range of the for loop needs to be adjusted to cover them. Here's one option which is moderately readable: `for my $i (0.. ($#$ref_a > $#$ref_b ? $#$ref_a : $#$ref_b) ) {` [download] Handily, extra elements appear in ref_a automatically as needed, so there's no need for a `\|\| []` on the first argument to push. Update: Re-reading the thread made me realise that because of the autovivification in ref_a, ikegami's suggestion does acheive all this (I think) but much more subtly. Too subtle for me the first time round ;-) -- use JAPH; print JAPH::asString();	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: Undefined Array Reference
by wol (Hermit) on Apr 23, 2009 at 16:05 UTC

If this is what's needed then:

for my $i (0..$#$ref_a) {
    push @{$ref_a->[$i]}, @{$ref_b->[$i] || []};
}
[download]

@{$ref_b}

@{$ref_a}

$ref_b->[$i]

(I also tried to use || last there (ie exit the loop early) but that comes up with a "bizarre" error message.)

If it's also possible for ref_b to have more members than ref_a, and the extras should be tacked on verbatim, then the range of the for loop needs to be adjusted to cover them. Here's one option which is moderately readable:

for my $i (0.. ($#$ref_a > $#$ref_b ? $#$ref_a : $#$ref_b) ) {
[download]

|| []

Update: Re-reading the thread made me realise that because of the autovivification in ref_a, ikegami's suggestion does acheive all this (I think) but much more subtly. Too subtle for me the first time round ;-)

--
use JAPH;
print JAPH::asString();

[reply]
[d/l]
[select]