Re: Re: Fill Arbitrary Array

I don't know which arrays are filled with this code :(

sub fill_array(\@)
{
       my ($right_array) = @_;

       # ...

       while (my @row = $sth->fetchrow_array())
       {
             push (@$right_array, \@row);
       }

       print "Values: @$right_array\n";        #Works!
}


fill_array(@name);

foreach my $entry (@name) {
   print "$entry\n";        #Remains empty...
}
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Re^3: Fill Arbitrary Array by tadman (Prior) on May 02, 2002 at 17:22 UTC
It should fill whatever array you pass to it, which in this case is `@name`. The reason this can be done is because of the way the sub is declared, in particular, the `(\@)` definition means that the first parameter is an array reference. This way, instead of passing a copy of the `@name` array, a reference to it is passed, allowing you to manipulate it. With that in mind, I'm surprised that you get "nothing". `@name` should be filled with array references, these sub-arrays that contain the various rows. Using your code, since you are not de-referencing them, you should see something like this: `ARRAY(0x80fe5a8) ARRAY(0x80fe5d2) ARRAY(0x80fe6f4)` [download] The reason is you are printing an array reference as a string, which isn't going to work. A solution is to either use the venerable Data::Dumper or just deference it: `# Data::Dumper saves the day again use Data::Dumper; print Dumper (\@name); # De-reference it and treat it as an array foreach my $row (@name) { print join (',', @$row),"\n"; }` [download] I'm not sure how familiar you are with references, but here's a 5 second intro: `my @array = qw[ 1 2 3 ]; my $array_ref = \@array; # Backslash makes a reference my @array_copy = @$array_ref; # @ de-references array reference $array[2] = 4; # Modifies @array directly print $array_ref->[2]; # Should be '4' now $array_ref->[1] = 5; # Modifies @array by reference print $array[1]; # Should be '5' $array_copy[1] = 6; # Modifies @array_copy, not @array print $array[1]; # Still '5'` [download]	[reply] [d/l] [select]

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Re^3: Fill Arbitrary Array
by tadman (Prior) on May 02, 2002 at 17:22 UTC

@name

(\@)

@name

ARRAY(0x80fe5a8)
ARRAY(0x80fe5d2)
ARRAY(0x80fe6f4)
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Data::Dumper

# Data::Dumper saves the day again
use Data::Dumper;
print Dumper (\@name);

# De-reference it and treat it as an array
foreach my $row (@name)
{
     print join (',', @$row),"\n";
}
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my @array      = qw[ 1 2 3 ];
my $array_ref  = \@array;      # Backslash makes a reference
my @array_copy = @$array_ref;  # @ de-references array reference

$array[2]       = 4;   # Modifies @array directly
print $array_ref->[2]; # Should be '4' now
$array_ref->[1] = 5;   # Modifies @array by reference
print $array[1];       # Should be '5'
$array_copy[1]  = 6;   # Modifies @array_copy, not @array
print $array[1];       # Still '5'
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