I'm a Perl beginner having trouble with arrays of arrays. When I define an AoA using a named AoA, both array names seem to refer to the same AoA. For example, if I first define @aoa1 with an anonymous AoA and then define @aoa2 with "my @aoa2 = @aoa1;", the modification of @aoa2 undesirably modifies @aoa1 (and vice versa).

The script below demonstrates this problem:

    use strict;
    use warnings;

    my @aoa1 = (                  # define @aoa1 w/ anonymous AoA
            ["-","-","-"],
            ["-","-","-"],
            ["-","-","-"],
        );
    
    # my @aoa2 = (                # define @aoa2 w/ anonymous AoA
    #         ["-","-","-"],
    #         ["-","-","-"],
    #         ["-","-","-"],
    #     );
    
    my @aoa2 = @aoa1;             # define @aoa2 w/ named AoA
    
    # $aoa1[1][1] = '@';          # modify @aoa1
    
    $aoa2[1][1] = '@';            # modify @aoa2
    
    printAoa( "aoa1", @aoa1 );    # print @aoa1
    printAoa( "aoa2", @aoa2 );    # print @aoa2
        
    exit;
    
    sub printAoa {
        my ( $aoaName, @aoa ) = @_;
        my $row;
        my $col;
    
        print "*** $aoaName ***\n";
    
        for $row ( 0 .. 2 ) {
            for $col ( 0 .. 2 ) {
                print "$aoa[$row][$col] ";
            }
            print "\n";
        }
        print "\n";
    }
[download]

I would expect the above script to print:

    *** @aoa1 ***
    - - - 
    - - - 
    - - - 
    
    *** @aoa2 ***
    - - - 
    - @ - 
    - - -
[download]

Instead, I get:

    *** @aoa1 ***
    - - - 
    - @ - 
    - - - 
    
    *** @aoa2 ***
    - - - 
    - @ - 
    - - -
[download]

It's as if @aoa1 and @aoa2 refer to the same AoA. When "$aoa2[1][1] = '@';" is commented out and "$aoa1[1][1] = '@';" is activated, the output is the same.

The only way I can get @aoa1 and @aoa2 to behave as I'd like is to define both of them with anonymous AoA's. If you comment out "my @aoa2 = @aoa1;" and uncomment the lines above it, the script produces the desired output. This is all well and good, but in my actual script, I need to define AoA's from named AoA's rather than anonymous ones.

Any suggestions would be greatly appreciated.

Thanks,
Andrew

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