thanks again - GH
if I don't use a loop it seems that it only processes 1st two lines.
is there another way I can process the file without a loop?
On Mon, 18 Oct 2004 19:02:04 +0200, Gunnar Hjalmarsson
<[EMAIL PROTECTED]> wrote:
> Alden Meneses wrote:
> > here is my updated code
> >
> > use strict;
> > use warnings;
>
> Yeah!! :)
>
> > while(<IBDIN>){
> > my @array_a = split ' ', <IBDIN>;
> > my @array_b = split ' ', <IBDIN>;
> > compare_array();
> > }
>
> By declaring the arrays within a while loop, they are not accessible
> outside the loop. That's why Perl complains. (Suggested reading, since
> you seem not to be used to strictures:
> http://perl.plover.com/FAQs/Namespaces.html)
>
> This is what I first suggested:
>
> my @array_a = split ' ', <IBDIN>;
> my @array_b = split ' ', <IBDIN>;
> compare_array();
>
> i.e. no loop at all. If you prefer a while loop, two named arrays is not
> very suitable. In that case, you may use an array of arrays instead:
>
> my @arrays;
> while(<IBDIN>){
> @{ $arrays[$.] } = split ' ';
> }
> compare_array();
>
> But if you are not familiar with Perl data structures, why not stick to
> the option without a while loop.
>
> > sub compare_array {
> > my (%seen, @bonly);
> > @[EMAIL PROTECTED] = (); # build lookup table
> > foreach my $item (@array_b){
> > push(@bonly, $item) unless exists $seen{$item};
> > }
> > print "@bonly \n";
> > }
>
> Since you now are using a subroutine, I'd like to make a comment with
> respect to style. It's good programming practice to pass variables to a
> subroutine rather than having it process file scoped variables. With
> that in mind, I'd suggest the following:
>
> open IBDIN, "<$file" or die "cannot open $file $!";
> my @array_a = split ' ', <IBDIN>;
> my @array_b = split ' ', <IBDIN>;
> close IBDIN;
>
> compare_array( [EMAIL PROTECTED], [EMAIL PROTECTED] );
>
> sub compare_array {
> my ($ref_a, $ref_b) = @_;
> my (%seen, @bonly);
> @seen{ @$ref_a } = (); # build lookup table
> foreach my $item ( @$ref_b ) {
> push (@bonly, $item) unless exists $seen{$item};
> }
> print "@bonly \n";
> }
>
> --
>
>
> Gunnar Hjalmarsson
> Email: http://www.gunnar.cc/cgi-bin/contact.pl
>
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