Re: what is @$varname in perl

[perlfan]

It seems like you're writing your arrays as array references just so you can avoid creating a reference out of a non-reference.

You have:

    foreach $line (@lines){
        chomp $line;
        $count++;
        next unless $count; # skip header in csv 
        my $row;
        @$row = split(/,/, $line );
        push @$sheet2 , $row;
    }

But if you ask me, it'd be tons more clear if you did this:

my @sheet2 = ()

# ....
    
    foreach $line (@lines){
        chomp $line;
        $count++;
        next unless $count; # skip header in csv 
        my @row = ();
        @row = split(/,/, $line );
        push @sheet2 , \@row;
    }

Another example is:

@$sheet2 = ();

Should be:

@sheet2 = ();

or

$sheet2 = [];

It seems to me you're conflating scalars, arrays, and references. Cleaning up the code and being consistent will go a long way in dispelling your confusion.

[sandy105]

i read up on reference and understand a scalar is assigned as reference :

my @array = (1, 2, 3, 'four');
    my $reference = \@array;

i modified using your suggestion as below

foreach $line (@lines){
            chomp $line;
            $count++;
            next unless $count; 
            my @row = ();
            @row = split(/,/, $line );
            push @sheet2 , \@row;
        }

        foreach my $row ( sort {$a->[0] cmp $b->[0] || $a->[1] cmp $b-
+>[1]}  @sheet2 )             #sorting based on date ,then stockcode
        {          
            chomp $row;
            print hanw join (',', @$row ),"\n";
        }

then why assign @sheet2 as reference

[2teez]

this :

        ...
        my $row;
        @$row = split(/,/, $line );
        push @$sheet2 , $row;
        ...

OR

    ...
    my @row = ();
    @row = split(/,/, $line );
    push @sheet2 , \@row;
    ...

Could be written like this in one line instead of three

   ...
   push @sheet2, [ split(/,/, $line ) ];
   ...

And there is no need for the array variable row at all.
You could use Data::Dumper to view your variable @sheet2 to confirm.

[perlfan]

push @sheet2 , \@row;

You're pushing a reference to @row as an item into @sheet2. In order to create complex data structures (array of arrays, array of hashes, etc) you need to assign references.