http://www.perlmonks.org?node_id=1227848

Silt has asked for the wisdom of the Perl Monks concerning the following question:

I found a problem where I get a different result when printing an array after calling a function, that shouldn't be able to change the array. I got the issue down to this:
use strict; use warnings; main(); sub main { problem([[0,1,2],[3,4,5],[6,7,8]]); } sub problem { print3DArray("\@_",@_);#Output: 0 1 2 3 4 5 6 7 8 reverseArray(@_); print3DArray("\@_",@_);#Output: 6 7 8 3 4 5 0 1 2 } sub reverseArray { for(my $i=0;$i<scalar(@_);$i++){ @{$_[$i]} = reverse @{$_[$i]}; } } sub print3DArray { print shift @_, ":\n"; for(my $i=0;$i<scalar(@_);$i++){ print2DArray(@{$_[$i]}); } } sub print2DArray { for(my $i=0;$i<scalar(@_);$i++){ for(my $j=0;$j<scalar(@{$_[$i]});$j++){ print $_[$i][$j]," "; } print "\n"; } print "\n"; }
@_ should stay the same, since I didn't return anything. I would appreciate any help! Thanks!