Accessing element of array of arrays

[perlqs]

Hi. I'm a relatively new Perl programmer, and I'd like some help working with two arrays of arrays. I want to store a value from the first one, @AoA1, into the second one, @AoA2, without changing @AoA1. At first I was trying $AoA2[foo][bar] = $AoA1[foo][bar]. Now, I don't even really understand what's happening when I use the [][] indexing - I think I end up assigning a reference instead of a value - but the effect is that when I change that value of @AoA2 again it changes the corresponding value of @AoA1, which is not what I want. So how do I dereference the value I want from @AoA1?

 

[prex1]

Please post the relevant part of code you are using: it doesn't work the way I understand you.

Franco

http://www.xcalcs.com

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http://www.megamag.it

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[KevinADC]

this is not even possible unless foo and bar are constants with a numeric value:

$AoA2[foo][bar] = $AoA1[foo][bar]

array indexes use numbers, starting with zero and going to whatever your computers memory can handle.

If you have @array1 and want to store a copy of the array in another array just assign it to another array:

@array2 = @array1;

Then you can change @array2 all you want without affecting the original array.

If you have some different situation you need to provide more details, some sample data is almost always helpful.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[perlqs]

This should demonstrate what I'm trying to do:

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

my @AoA1 = ([1, 'a'], [2, 'b']);

my @AoA2;
push @AoA2, @AoA1;

$AoA2[0][0] = $AoA1[0][0];
print "$AoA1[0][0], $AoA2[0][0]\n";

$AoA2[0][0] ++;
print "$AoA1[0][0], $AoA2[0][0]\n";

Notice that when $AoA2[0][0] is augmented, $AoA1[0][0] is as well. The desired output would be:

1, 1
2, 1

instead of

1, 1
2, 2.

 

[prex1]

This occurs because the elements of [tt]@AoA1[/tt] are references to arrays, not real arrays: use parentheses instead of square brackets.

Franco

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads