Perl: Skip line N while reading a file

Question

How would I skip say line 9 while I'm parsing a text file?

Here's what I got

use strict; use warnings;
open(my $fh, '<', 'file.txt') or die $!;
my $skip = 1;
while (<$fh>){
    $_=~ s/\r//;
    chomp;
    next if ($skip eq 9)
    $skip++;
}

Not sure if this works but I'm sure there's a more eloquent of doing it.

I can only assume that `s/\r//` is there because you have [␍␊](http://stackoverflow.com/a/3098328/1337) terminated lines. If that is the case you should open your file with the [`:crlf`](http://perldoc.perl.org/functions/open.html) layer (`open( my $fh, '<:crlf', 'file.txt')` ) — Brad Gilbert, Apr 13 '13 at 06:17

score 13 · Accepted Answer · edited Apr 03 '13 at 17:11

13

You can use $.:

use strict; use warnings;
open(my $fh, '<', 'file.txt') or die $!;
while (<$fh>){
    next if $. == 9;
    $_=~ s/\r//;
    chomp;
    # process line
}

Can also use $fh->input_line_number()

edited Apr 03 '13 at 17:11

Sinan Ünür

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answered Apr 03 '13 at 16:54

imran

1,560
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2

okay so `$.` is a special variable that stores the current input line number of the last filehandle that was read. I just read that that from this [SITE](http://www.kichwa.com/quik_ref/spec_variables.html). I didn't know that until today. Thanks – cooldood3490 Apr 03 '13 at 16:58
4

@cooldood3490 The correct place to check is the documentation installed along with your `perl`: `perldoc -v '$.'` Current version of the documentation is available on [perldoc.perl.org](http://perldoc.perl.org/perlvar.html#%24.) I would recommend staying away from web sites that spell the name of the language incorrectly. – Sinan Ünür Apr 03 '13 at 17:12
Instead of `$_=~ s/\r//;`, write `s/\r//`. Better yet, write `while (my $line = <$fh>) { $line =~ s/\s+\z//; }`. – Sinan Ünür Apr 03 '13 at 17:14
3

You don't even have to use [`$.`](http://perldoc.perl.org/perlvar.html#%24. "perldoc -v '$.'") directly, you can use [`..`](http://perldoc.perl.org/perlop.html#Range-Operators "perldoc perlop") in scalar context. `next if 9..9;` If you need to skip more lines: `next if 9..12;` – Brad Gilbert Apr 13 '13 at 06:08

Perl: Skip line N while reading a file

1 Answers1