From: Christopher Yee Mon <[EMAIL PROTECTED]>
> I have a bit of Perl homework where we got a code sample. I can see what
> the code sample is doing except for two little bits
>
> There's a part that has $row->[$i] and a part that has @$row . What do
> these two parts mean?
$row->[$i] is the $i-th element of the array referenced by $row and
@$row is the array referenced by $row.
Another way to write the first thing would be ${$row}[$i].
> The code sample turns csv into fixed width so it reads each line of the
> file into an array @rows. Then in a for loop
>
> for $row (@rows) {
That should be
for my $row (@rows) {
You should put
use strict;
on top of your scripts and declare all variables. And you should
declare them for the smallest scope possible. In the case of $row,
just for the loop.
> There's another for loop
>
> for $row (@rows) {
> ~ for ($i = 0; $i < @$row; i++) {
> ~ $w = length $row->[$i]
> ~ ...
>
> I'm assuming that the $row is itself another array
It's a reference to one
> or can be treated as one and @$row can give you a number of the
> elements in it
No, the @$row is the array referenced by $row, but an array, in
scalar context, returns its length. So just like
my $len = @array;
sets $len to the number of elements in @array,
my $len = @$arrayref;
sets it to the number of elements in the array referenced by
$arrayref. The concept of context takes some getting used to, but
it's one of the best inventions of Perl.
> and $row->[$i]
> is some sort of deferencing mechanism.
Right.
> The perlop page seemed a bit
> cryptic to me as to what the arrow operator does exactly and I could
> search for the use of @ in that context.
See perlref and perldsc
HTH, Jenda
===== [EMAIL PROTECTED] === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed
to get drunk and croon as much as they like.
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