Re: Comparing file contents, the perl way

beast wrote:
> Good morning,

Hello,

> I have 2 files which contains some IDs. Basically I want to search ID
> in the file A which is missing on the file B.
> 
> This program is ugly, but its work :-)
> ------------
> use strict;
> 
> my $target_file = "B.txt";
> while(<>) {
>    chomp;
>    my $res = `grep $_ $target_file`;
>    print "$_ is missing\n" if ! $res;
> }
> ------------
> 
> I'm trying to found another solutions which more perlish and efficient.
> So far im relying that ID should be same digits on the both file,
> because "123" will match "1234" :-(
> 
> File contents is around 20k - 30k lines, so i must consider the
> performance and memory usage also.
> 
> A.txt
> -----
> 12345
> 56789
> 32134
> 62134
> 42134
> 52134
> 12234
> 
> B.txt
> -----
> 12234
> 42134
> 82134
> 32134

$ cat A.txt
12345
56789
32134
62134
42134
52134
12234
$ cat B.txt
12234
42134
82134
32134
$ grep -f A.txt -wv B.txt
82134



John
-- 
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order.                            -- Larry Wall